OpenPrinting/Color Management

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DRAFT Subject to change.

What is needed for the color managed printing in the new PDF based printing work flow?

  • Input profiles embedded into the PDF print documents, either per object or per document. The application creating the print document is responsible for correctly embedding these input profiles.
  • In addition PDF print documents need to be "generic PDF" to allow for overriding the OutputIntent settings in the PDF file.
  • Output profiles. If these are embedded into the print document then these will over ride any cupsICCProfile defaults.
  • Talkback mechanism, to provide a nice simulated print preview to a user.
  • Full ICC support in the PDF to raster conversion library that is compliant with the current PDF standard.
  • A pdftoraster CUPS filter that makes full use of these color management features.
  • The Common Printing Dialog should have UI features that allow users to control how color management works. This would include:
    • The ability to enable or disable printer color management to calibrate and profile a printer system.
    • The ability to enable or disable the automatic use of the PPD default profiles as specified by the cupsICCProfile entries in the PPD file.
    • If automatic OOD based profile selection is disabled the ability for users to select specific printer profiles including those listed in cupsICCProfile PPD entries and those located in other locations such as /usr/share/color/icc, /usr/local/share/color/icc or ~/.color/icc
    • The ability to specify rendering intents and for relative colorimetric intend to enable/disable black point compensation.

What components do we have to realize a color managed printing work flow?

  • CUPS as a transportation layer
  • The new pdftoraster CUPS filter that is being worked on.
  • Ghostscript to do compliant CIEbased and ICCbased rendering.
    • The current version of GhostScript uses Argyll code with ICC v2 support. So it partly supports the functionality needed.
    • Work is underway to use Lcms with ICC v2 + ICC v4 support in a future version of Ghostscript. This should allow GhostScript to do everything needed with respect to color managing a PDF printing work flow.
  • Oyranos and various user front ends to Oyranos such as Kolor Manager for KDE, for user settings. This implies that the Common Printing Dialog needs to use Oyranos to pick up user printing color management preferences.
  • Common Printing Dialog support for color management features are part of the current CPD design documents but these features are currently unimplemented and lack detailed specifications.
  • The current Common Printing Dialog does do a preview but only of a limited size. When it starts using a PDF specification complaint PDF rendering library it should be able to at least do document color space to monitor color space corrected previews. Perhaps at a later time a soft proofing preview could be added.
  • The Alton Test Suite has a set of PDF documents to confirm correct functioning of these systems.